DOC: fix a few typos

include/types/proto_http.h: hwen -> when
include/types/server.h: SRV_ST_DOWN -> SRV_ST_STOPPED
src/backend.c: prefer-current-server -> prefer-last-server

Signed-off-by: Godbach <nylzhaowei@gmail.com>
(cherry picked from commit f2dd68d0e047cdd433d698f044bb2d327886fc66)
diff --git a/include/types/proto_http.h b/include/types/proto_http.h
index c53c7fd..1c7f4a6 100644
--- a/include/types/proto_http.h
+++ b/include/types/proto_http.h
@@ -70,7 +70,7 @@
 
 /* indicate how we *want* the connection to behave, regardless of what is in
  * the headers. We have 4 possible values right now :
- * - WANT_KAL : try to maintain keep-alive (default hwen nothing configured)
+ * - WANT_KAL : try to maintain keep-alive (default when nothing configured)
  * - WANT_TUN : will be a tunnel (CONNECT).
  * - WANT_SCL : enforce close on the server side
  * - WANT_CLO : enforce close on both sides
diff --git a/include/types/server.h b/include/types/server.h
index c419b40..02983d6 100644
--- a/include/types/server.h
+++ b/include/types/server.h
@@ -43,7 +43,7 @@
 #include <types/checks.h>
 
 
-/* server states. Only SRV_ST_DOWN indicates a down server. */
+/* server states. Only SRV_ST_STOPPED indicates a down server. */
 enum srv_state {
 	SRV_ST_STOPPED = 0,              /* the server is down. Please keep set to zero. */
 	SRV_ST_STARTING,                 /* the server is warming up (up but throttled) */
diff --git a/src/backend.c b/src/backend.c
index 6fe03f9..ada8370 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -552,7 +552,7 @@
 	       (__objt_server(conn->target)->nbpend + 1) < s->be->max_ka_queue))) &&
 	    srv_is_usable(__objt_server(conn->target))) {
 		/* This session was relying on a server in a previous request
-		 * and the proxy has "option prefer-current-server" set, so
+		 * and the proxy has "option prefer-last-server" set, so
 		 * let's try to reuse the same server.
 		 */
 		srv = __objt_server(conn->target);